<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    function foo(b) {
      let a = 10;
      return a + b + 11;
    }

    function bar(x) {
      let y = 3;
      return foo(x * y);
    }

    console.log(bar(7)); // 返回 42
  </script>
</body>
</html>